Fibrous products and textiles produced therewith



Oct. 4, 1949. c. s. FRANCIS, JR 2,483,405

FIBROUS PRODUCTS AND TEXTILES PRODUCED THEREWITH Filed Nov. 20, 1943 INVENTOR C/IRLETO/V 6. FRHNCIS, .TR.

BMW

ATTORN EY Patented Oct. 4, 1949 ruinous PRODUCTS AND 'rEx'rmns rno uccn THEREWITH Carleton 8. Francis, Jr., West Harwich, Mass assignor, by mesne assignments, to American iscose Corporation, Wilmington, DeL, a corporation of Delaware Application November 20, 1943, Serial No. 511,024

The present invention relates. in general, to fibrous products, such as textiles, and more particularly to such fibrous products formed at least of two types of fibres, one of which can be rendered adhesive to bind the fibres together. The invention also relates to correlated improvements designed to enhance the quality, utility, structure and properties of such products without detrimentally affecting the flexibility, porosity or other desirable characteristics inherent in the products.

The present application is a continuation-in-' part of my co-pending U. 8. application Serial No. 381,292, filed March 1, 1941 (now Patent No. 2,357,292), which discloses fibrous products and structures formed from at least two types of fibres, one of which can be rendered adhesive to bind the fibres together. The present invention also relates to textiles of the types disclosed and claimed in U. 8. Patents Nos. 2,252,999 and 2,253,000, which textiles areformed from at least two types of fibres, one of which can be rendered adhesive to bind uct. Potentially adhesive fibres heretofore manufactured and sold are formed by extrusion through spinnerettes such as are used in the manufacture of rayon. Such extrusion processes are limited to the use of certain plastic compositions having proper filtering characteristics, requisite solubility, viscosity, wet and dry tensile strength and other characteristics necessary for spinning the materials into continuous filaments. Moreover, the filaments thus produced must fall within a narrow range as to denier and must be cut to stable lengths within a narrow range imposed by their use on conventional textile and felting equipment, that is, the cut staple fibres must be capable of being carded, drafted, spun and felted on standard equipment used for making textiles and felts. Moreover, it is not practi fibres in the prod-* 6 Claims. (01. 154-54) cal, in many cases,. to incorporate plasticizers, Y

hardening agents and the like in the plastic composition before extrusion since such additions change the spinning properties and the products so produced can seldom be sold as regular textile fibres but must be limited to special uses as in the inventions of my co-pending applications,

thus decreasing the market and increasing the cost of such specially formulated fibres. Accordingly, the combination of the above-mentioned factors limits the artificial fibres available to a few kinds of thermoplastic materials, to a narrow range of fibre lengths and deniers, to certain kinds of plasticizers and puts the thermoplastic fibres so produced in a high price range.

of other fibres in the product.

It is a further object of the invention to provide improved fibrous products of the type just mentioned without limitation as to the nature of the material'from which the potentially adhesive fibres can be'made, or of the plasticizers which may be incorporated in such fibres.

It is a further object of the invention to provide fibrous products of the type described'without limitation as to length or denier of the potentially adhesive fibres.

It is another object of the improved textiles comprising at least two types of fibres, one of which is adapted to be rendered adhesive for binding fibres together in the product.

Other objects of the invention will in part be obvious and will in part appear hereinafter. I

According to the process claimed in my copending application Serial No. 381,292 (now Patent No. 2,357,292) fibrous products are made by associating discontinuous potentially adhesive organic plastic fibres, concurrently with their formation, with non-adhesive fibres, more par- .ticularly by dispersing into a gas, a potentially adhesive fibre-forming material to form fibres, associating the potentially adhesive fibres concurrently with their formation with another type of fibre, fabricating said mixture of fibres into a fibrous structure, such as a textile, and thereafter activating the potentially adhesive fibres to bind fibres in the product. In contrast to prior extrusion methods, the potentially adhesive material in that process is formed into fibres by dispersing it, as by spraying a plastic or molten mass of the material or a solution of the material in a suitable solvent into a gaseous atmosphere, under such conditions that a multiplicity of filamentary structures are produced as described in detail hereinafter.

According to the present invention, there is provided as an article, fibrous products and fibrous structures comprising a multiplicity of v potentially adhesive fibres admixed with a multiplicity of non-adhesive fibres, the fibres being preferably commingled in an unarrayed manner, the potentially adhesive fibres varying in diame er and length and contacting the other fibres at substantially more as continuous filaments and then cut into staple invention to provide points than an equal weight of the fibre-forming material when spun fibres. It is to be understood that the articles of the present invention may be made in a number of ways and are not limited to products produced by the processes of my co-pending application Serial No. 381,292 filed March 1, 1941 (now Patent No. 2,357,292).

In the following specification and in the claims, the term "fibre or "fibres" when used in reference to the potentially adhesive material is intended to include any fibril and discontinuous fibres, whether independent from one another or adhered at spaced points to form a felted product or reticulated structure. The expression fibrous product includes any heterogeneous mixture of at least two types of discontinuous fibres with or without structure and the term fibrous structure" includes textile products such as fabrics, felts and paper as well as rovings, yarns, threads and cords formed from said mixture of fibres.

Among the textiles which may be produced are yarn, single or plied, threads and cords of all kinds which may be used as warp or as filler (weft) in making fabrics, or in association with other yarns of like or unlike character, in weaving, knitting, netting, lacing and other textile constructions, and when doubled or twisted with other yarns, for the preparation of threads and cords of all kinds.

The term adhesive includes sticky, cementitious, agglutinous, or tacky conditions. The term "non-adhesive fibres includes those fibres which, although they may be rendered adhesive by some treatment, are not rendered adhesive under the conditions used to activate the potentially adhesive fibres associated therewith.

For a more complete understanding of the invention, reference should be had to the accompanying drawing, in which:

Fig. 1 is a side elevation, partly in section, of one embodiment of suitable means for forming the potentially adhesive fibres of the invention;

Fig. 2 is a side elevation, partly in section, of one-embodiment of means for carrying out the invention in the fabrication of flat felts and papers;

Fig. 3 is a side view, partly in section, of a suitable means for commingling fibres in the fabrication of one embodiment of the fibrous product of the invention;

' Fig. 4 is an enlarged perspective view of one of the potentially adhesive fibres used in the fibrous products of the invention; and

Fig. 5 is an enlarged view in cross-section of a layer of the commingled fibres in one embodiment of the product.

Among the non-adhesive fibres which may be employed are natural fibres such, for example, as wood fibres, cotton, flax, jute,- kapok, wool, hair and silk; and synthetic fibres, such, for ex ample, as cellulosic fibres, such as cellulose hydrate, cellulose derivatives, as cellulose esters, mixed cellulose esters, cellulose ethers, mixed cellulose ester-ethers, mixed cellulose ethers, cellulose hydroxy-alkyl ethers, cellulose carboxy-alkyl ethers, cellulose ether-xanthates, cellulose xanthofatty acids, cellulose thiourethanes; natural and synthetic rubber and derivatives thereof; fibres made of alginic acid, gelatine, casein; and mineral fibres such, for example, as spun glass, asbestos, mineral wool, and the like; and fibres made of natural and synthetic resins which are not rendered tacky when the potentially adhesive resin fibres are rendered tacky; also fibres and filaments made by slitting, cutting or shredding nonflbrous films, such as cellophane.

For producing the potentially adhesive fibres there may be employed any potentially adhesive fibre-forming substance in a fiowable condition, i. e. in a plastic or molten state or solution, such, for example, as a cellulose derivative, a natural resin or rubber, either singly or in compatible admixtures. Among the cellulose derivatives which are suitable are, for example, cellulose esters, cellulose ethers, mixed cellulose esterethers, mixed cellulose esters, mixed cellulose ethers, and mixtures of cellulose derivatives, all of which should be of the type which is soluble in volatile organic solvents.

Various natural resins may be employed since such substances may be formed into fibres by spraying although they are unsuitable for extrusion into filaments. Suitable natural resins are, for example, shellac, dammar, copal, and the like. Any of the synthetic resins which are soluble in organic solvents may be employed, such, for example, as polymers of single organic compounds, such as cumarone, indene hydrocarbons, chloroprene, vinyl alcohol, vinyl chloride, vinyl acetate, styrene, esters of acrylic acid, also thermoplastic resins formed by condensation of two or more substances, such, for example, as sebacic acid and glycerol, sulphur olefine resins, resins formed from dicarboxylic acids and diamines (nylon type), also thermosetting resins in the thermoplastic state, such, for example, as phenol aldehyde resins, urea aldehyde resins, melamine aldehyde resins, sulfonamide aldehyde resins, alkyd resins, drying oil-modified alkyd resins, also synthetic rubber or synthetic elastomers herein included in the term resins, such, for example, as

V polymerized butadiene, polymerized olefine polysulfides, polymerized isobutylene, also resins formed by copolymerization of two or more compounds, such, for example, as copolymers of vinyl halides and vinyl acetate, copolymers of vinyl halides and an ester of acrylic acid, copolymers of a vinylidene chloride and vinyl acetate (Saran),

the polymer of a vinyl compound and'styrene, copolymers of polyvinyl alcohol and a halide, copolymers of acrylonitrile and butadiene, copolymers of butadiene and isobutylene, also resins derived from rubber, for example, a chlorinated rubber of the type of Parlon, the reaction product of a hydrogen chloride and rubber, e. g. Pliolite, and cyclized rubber derivatives formed by treating rubber in the presence of stannlc chloride, e. g. Plioform"; also fibres made from rubber latex, crepe rubber, gutta percha, balata, and the like.

Further, the potentially adhesive fibres may be formed from mixtures of the cellulose derivatives with resins or rubber, such, for example, as a mixture of cellulose nitrate and an acrylic acid resin, or a mixture of benzyl cellulose and a vinyl resin, or a mixture of ethyl cellulose and shellac. The invention is particularly well adapted for forming the potentially adhesive fibres from compositions of cellulose derivatives, resins, rubbers, and their mixtures, which compositions are not adapted for forming fibres by extrusion through artificial silk spinnerettes, since such factors as filtering characteristics, solution viscosity and fibre tenacity are not critical in the present fibre-forming process.

In making up the fibre-forming solution. the fibre-forming material may be dissolved in a suitable organic solvent which will volatilize rapidly at moderately elevated temperatures. Suitable solvent mixtures may be selected by those skilled in the art having regard for the nature of the fibre-forming substance. As an alternative to dissolving the substance in a suitable solvent, the fibre-forming material may be heated until plastic or molten and the plastic or molten mass dispersed into fibres as hereinafter described.

The proportion of the fibre-forming substance to the solvent will depend, inter alia, upon the nature of the fibre-forming material, the type of dispersing device employed'and the type of fibres desired to be produced. In general solution concentrations of from 5% to 50% will be suitable for most fibre-forming substances and conditions.

To the fibre-forming material or solution thereof, there may be added suitable plasticizers, hardening agents for the resins, latent activating agents, dyes, pigments, moth-proofing agents,

fireproofing agents, water-proofing agents, and the like. In particular, it may be desirable to add to the material or solution suitable substances for lowering the thermal softening point of the fibres produced, such, for example, as plasticizers, soft resins, and the like. Among suitable plasticizers for this purpose are dibutyl tartrate, ethyl phthallyl ethyl glycolate, while suitable soft resins are polyvinyl acetate, ester gum, coumaron resin, and the lower polymer of alkyd resins.

Generally speaking, the fibre-forming process of the invention comprises dispersing the fibrei'orming material while in fiowable condition, that is, in solution or plastic or molten condition, into a gaseous atmosphere under sufiicient pressure to form a multiplicity of fibres. When a solution is employed, the dispersion is preferably into a gaseous atmosphere which is heated sufiiciently to evaporate the solvent rapidly. In this embodiment, the organic solvent may be wasted or recovered in a suitable manner as by scrubbing or absorption. When a molten mass'is dispersed, the atmosphere is preferably cooled so as to cause a rapid congealing or solidification of the fibre-forming material.

To carry out the fibre-forming process there may be used any suitable means for'converting the flowable' substance or composition into fibrous form and the invention is not to be limited to the particular means hereinafter described.

In the now preferred embodiment of the invention, the fibre-forming composition is dispersed into a heated gaseous atmosphere by means of a spray gun or atomizer comprising, in combination, means to supply the fluid composition under pressure to an orifice, means to supply one or more streams of air or gas at a point adjacent the fluid orifice so as to disperse and disrupt the stream of fluid issuing from the orifice.

There is shown in Fig. 1 a conventional type of spray gun, hereinafter designated generally by the reference character I, and comprising essentially a container 2 adapted to hold the fibreforming composition from which it is' forced by air pressure through the supply line 3 to the chamber 4 from which the composition is discharged through the orifice 5. The air is supplied through the line 6 to the air chamber I which surrounds the chamber 5 and terminates in a plurality of orifices 8 positioned adjacent the orifice5. The trigger or handle 9 is adapted to operate the pin valve In which opens the orifice 5 and the air valve II which opens the air line 6. As the stream of fibre-forming composition is discharged from the orifice 5, it is disrupted by the force of the tangential streams of air discharged through the orifices 8. The size, shape and character of fibre produced by this spraying operation is a function, inter alia, of the viscosity of the solution, the pressure under which the solution and air are discharged, the angle with which the air streams contact the fluid stream, but these factors and their control are well known to those skilled in the art and can be adjusted to producevarious types of fibres without transcending the scope of the invention. When the fibre-forming material is plastic or molten, the material suitably heated to render it fiowable is caused to fiow into contact with an air stream which disperses the material into fibres, or is forced under pressure through an orifice into fibres and means may be provided to maintain the material fiowable to the point of dispersion.

In another embodiment, the non-adhesive fibres or the potentially adhesive fibres may be formed by electrical dispersion in a gaseous atmosphere. For example, a stream of the fibreforming material is caused to fiow into an electrically charged field, whereupon the stream is dispersed into a multiplicity of fibreswhich are attracted in the direction of an oppositely charged element, and the fibres so produced may be collected on the belt 24 of Fig. 2.

The fibres produced may be independent and separable from one another or they may adhere to each other at spaced points to form a more or less fibre web or reticulated structure depending upon whether. the fibre is inherently tacky or is still tacky due to its temperature or to the presence of residual solvent when the fibre contacts a fibre of like character.

Fig. 4 is a perspective view of a representative fibre formed by spraying. It should be noted that the ends 28 of the sprayed fibre are tapered in contrast to the square cut ends ex:- truded staple fibres. Also, the sprayed fibre is characterized by having an unequal thickness or denier throughout its length although the variations from the average thickness are not sufiiciently great to prevent its efiective use in the fibrous structures of the invention. While the fibre shown may be considered a representative average fibre, in the mass of fibres sprayed under given conditions there will be a substantial variation in the length of the individual fibres and in the thickness and denier which is another physical feature which differentiates the fibres from staple fibres cut from continuous filaments.

It is to be understood that when the formation of the above-described fibres takes place in the presence of non-adhesive fibres, that the potentially adhesive fibres may adhere to such other fibres, as well as vent is not completely removed from the fibre at the points of mixing and depositing. Accordmgly, it is possible in the present invention to form, mix and substantiall adhere or combine the fibres together in immediate sequence, that is, concurrently and continuously, merely by regulating the rate of evaporation of the organic solvent, the time elapsing between the formatlon of the potentially adhesive fibres and the point of contact withthe other fibres.

It should be noted that since the fibres are not carded but are deposited from a gaseous dispersion, they are intermingled in an unarrayed, manner which gives a product having uniform strength in all directions.

If desired, the formation of the potentially adto themselves if the solhesive fibres'may be carried out in a chamber separate from but connected with the chamber in which these fibres are associated, as by mixing, with the non-adhesive fibres. Thus, a single fibre-forming means may serve to supply fibres for. a plurality of different mixing chambers. However, the expression "concurrently with their formation as used herein includes forming and associating in immediate sequence without permitting the potentially adhesive fibres to settle before association.

The above-described fibre-forming processes may be employed for producing the non-adhesive fibres as well as the potentially adhesive fibres.

The expressions non-adhesive" and potentially adhesive as used in the specification and claims are relative terms which depend upon the particular activating treatment selected; as used in Example VII hereof, the term non-adhesive designates that fibre type which remains nonadhesive under the treatment which renders the other type adhesive.

The ratio of potentially adhesive fibre to other fibre may be varied over a wide range depending on the purpose for which the fibrous product is intended. In general, to preserve the inherent flexibility, porosity and texture of the product, a minor proportion of the potentially adhesive fibres is employed and preferably from 3% to by weight. In the production of certain products, for example, felts and textiles having reduced porosity or impermeability if desired, the potentially adhesive fibre present may constitute a major proportion, for example, up to 65% of the total fibres.

Referring to Fig. 2, fibre mixtures suitable for the manufacture of textile structures of the type of felts and paper may be produced by dispersing a fibre-forming composition by means of the spray gun I into a heated gaseous atmosphere contained in the chamber 20 into which is simultaneously blown non-adhesive felt or paper making fibres 2i through conduit 22 by means of a blower 23. The mixture of fibres falls downwardly in the chamber and comes to rest on the surface of an endless belt 24 made of flexible material such as textile, metal, leather or the like, which is positioned in a horizontal plane at the base of the chamber 20. The bat of mixed fibres is carried on the belt from the chamber and through pinch rolls 25 and 2B which compress the bat and enable it to be removed from the belt for activating or finishing operations to be hereinafter described. It the potentially adhesive fibres produced by spraying are thermoplastic, the rolls 25 and 26 may be heated sufllciently to activate the thermoplastic fibres, the fibres becoming deactivated when the felt passes from the rolls and becomes cool. The solvent evaporated from the fibreforming composition may be withdrawn from the chamber 20 through exhaust pipe 21 and wasted or recovered in aknown manner. When using potentially adhesive fibres which are activatableby means of an organic solvent, such solvent can be sprayed on the fibre bat as it is carried on the belt, as at point A, so that the fibres are in an adhesive condition when passing through the pressure rolls 25 and 26. In the manufacture of paper felts the belt 24 may be considered as comprising the wire screen of the paper making machine. Thus, the fibre-forming, mixing and felting steps in making the felts and papers are carried out concurrently and continuously, in immediate sequence, that is, in a simple and economical manner.

g In the apparatus shown in Fig. 2, the nonadhesive fibres may be produced from a solution of, or a plastic or molten fibre-forming material by use of a second spray gun positioned in the chamber 20 in place of the conduit 22. In this manner, novel fibrous products are capable of being produced entirely of a mixture of dispersed artificial fibres, one type of which is potentially adhesive and the other is non-adhesive.

In the manufacture of textiles, the forming and mixing of the potentially adhesive fibres with the textile fibres can be effected at any point prior to the completion of the spinning of the yarn, but in the preferred embodiment, the forming and mixing of the fibres takes place during or immediately after carding of the textile fibres. Referring to Fig. 3, the roll 35 represents the last or delivery roll on a conventional cotton carding machine, from which the doffer-blade 36 strips the thin layer of fibres to form continuously the gauze-like web 31 of cotton fibres. There is built around the last roll 35 and the web 31 a fibreforming and mixing chamber 20b, the web 31 being positioned adjacent the base of the chamber and a spray gun lb being positioned at the top of the chamber. The fibres formed by the spray gun fall downward in the chamber 20b, being aided by a down draft created by the withdrawal of the solvent through the pipe 38 in the base of the chamber. The potentially adhesive fibres are thus deposited on the thin web 31 of cotton fibres and are gathered between the folds of this web as it passes out of the chamber and through the usual funnel 339 and is delivered by the rolls 40 into the sliver can 4i. During the subsequent drafting, and spinning of the card sliver 42, the potentially adhesive fibres become suificiently admixed with the textile fibres to achieve the objects of the invention when the textile is simultaneously activated, compacted and otherwise finished. The potentially adhesive fibres may differ in length and diameter compared to the textile fibres. Moreover, since the potentially adhesive material is actually in fibrous form it does not sift out of the sliver or roving during drafting,

spinning, doubling, weaving or other textile operation prior to activation. The forming of the potentially adhesive fibres is effected concurrently and continuously with the mixing of such fibres with the non-adhesive textile fibres.

The sliver or roving formed from the mixture of potentially adhesive fibres and non-adhesive textile fibres is then formed into a singles yarn by drafting and spinning in the usual manner, and, if desired, such singles yarns may be doubled with each other or with other yarns to form a plied'yarn or cord 30 as shown in Fig. 5. Referring to Fig. 5, one or all of the singles yarns 3! may contain the potentially adhesive fibres. Before or after spinning and before or after doubling, the potentially adhesive fibres may be rendered adhesive to bind fibres in the product. Depending upon the percentage of the potentially adhesive fibres, the method of activation, and the disposition of the potentially adhesive fibres in the yarn, the yarn twist in the singles yarn may be stabilized and likewise one may stabilize the structure of the plied yarn or cord as a result of the activation. Owing to the fact that the potentially adhesive fibres formed by spraying may be finer than fibres heretofore produced by extrusion, it is possible to have a larger number of potentially adhesive fibres and therefore more points of contact using such sprayed fibres than would be possible with an equal weight of the same material when extruded in the form of continuous filaments and cut into staple fibres.

Apparatus similar to that shown in Fig. 3 may be employed in the manufacture of felts, in which case the web, after having had the potentially adhesive fibre deposited thereon, is not drawn into the funnel 39 but is withdrawn in web form and a bat formed therefrom in a desired manner.

The invention contemplates activating the potentially adhesive fibres and the activation may be in predetermined areas or uniformly throughout the product depending upon the effect desired; also, the textile may be subjected to two or more activating treatments either in sequence or separated by other treatments and textile operations. Among the methods which may be used for activation are the following, taken singly or together in appropriate combinations.

1. When the potentially adhesive fibres are thermoplastic, they may be activated by heat, for

example, by the use of dry hot air, contact with heated surfaces, or steam.

2. By applying to the fibrous mixture a solvent or swelling agent or mixtures thereof with diluents, under such conditions of concentration and temperature so as to render the potentially adhesive fibres tacky. For example, fibres of organic cellulose derivatives, such as cellulose esters may be rendered adhesive by solvents, such as acetone, ethyl acetate, butyl acetate and the like.

3. When the fibres are tacky at the time of activation, they can be activated by pressure alone.

4. A latent activating agent may be combined with the potentially adhesive fibres and/or with the non-adhesive fibres. Such agent may be rendered active by a subsequent treatment, such as chemical agents, heat or irradiation, thus producing a simultaneous activation of the potentially adhesive fibres. For example, fibres may be impregnated with a liquid which, at room temperature, is a non-solvent therefor but which, at a higher or lowerv temperature, is a solvent sufliciently active to render thepotentially adhesive fibres adhesive.

A plasticizer may be applied to the fibres and/or to the product before activation. The plasticizermay function to increase the fiexibility of the fibres and, when employed with thermoplastic fibres, the plasticizer may serve, in addition, to lower the thermal softening point. The plasticized thermoplastic fibres can be rendered adhesive by heating to a temperature below that at which the non-thermoplastic textile fibres associated therewith would be detrimentally affected by such heating. The plasticizer may be allowed to remain in the product or it may be removed by suitable means such as washing and extraction, thus again elevating the thermal softening point of the thermoplastic material and preventing reactivation upon ironing.

While the fibres are in an adhesive condition, the fibres are preferably subjected to a compacting treatmentto promote adhesion of the associated fibres at their points of contact and the deactivation treatment will depend, inter alia,

upon the nature and extent of the activating treatment and upon the proportion and kind of potentially adhesive fibres used. If activation has been accomplished by heat, deactivation may be accomplished by heating to a higher temperature as with thermosetting resins, or by cooling; and if activation is by means of a solvent, deactivation may involve extraction of the solvent as by washing, evaporation, decomposition; if

, in the product.

term compacting includes pressing, squeezing and tension. For example, mechanically applied pressure may be exerted on the activated material during and/or after activation, and/or during calendering, embossing, printing, drying and other operations involving the use of rollers.:-'

Compacting may be accomplished by twisting or stretching the yarns, threads, or cords with or without application of additional external presactivation has been accomplished by pressing, deactivation follows upon release of the pressure. The removal of the activating agent depends upon whether its presence in the product is desirable or objectionable.

The activating, compacting and deactivating treatments herein described may be carried out independently of, or simultaneously with, various treatments common to the fabrication, finishing and sizing of textile fabrics and materials.

Further, the products of the invention may at any time be embossed, calendered, moulded or otherwise shaped, in whole or in part, to deform the surface while the adhesive fibres are still tacky and then subsequently deactivated to set them with a desired form or surface condition to produce effects such as grain, lustre, smoothness or designs, by suitable means, used hot or cold, and with or without the aid of agents'which soften, swell or plasticize the material acted upon.

The fibrous products may be colored before, during or after activation, compaction and/or deactivation, by dyeing or printing, for example, with inks containing pigments or dyestuifs which are resistant to such treatments. If desired, the activating agent or the deactivating agent may be added to the dyebath or the printing ink.

The properties of the finished product depend upon various factors, such as the nature and proportion of potentially adhesive fibres; the extent of the activation thereof; the adhesive condition,

of the fibres during compacting; and the nature of the deactivation. The extent of activation, compacting and deactivation may be varied considerably, depending upon the relative proportions of the types of fibres, the properties of the potentially adhesive fibre and the effect desired The potentially adhesive fibres may be rendered superficially tacky; or made adhesive without losing their fibrous form; or rendered suificiently fluid to spread under pressure to form a film in which the other fibres are embedded. If the potentially adhesive fibres are rendered only slightly tacky, the frictional resistance between fibres will 'be increased and the strength improved. If the potentially adhesive fibres are rendered substantially adhesive, they will cohere to each other and adhere to the other face.

By way of illustrating but not by way of limiting. the invention, there will be given the following specific examples:

Example! To manufacture a textile yarn or a. thread by the present process, staple rayon fibres are carded, using the apparatus shown in Fig. 3. There is produced potentially adhesive fibres by spraying through the spray gun lb a solution of 40 parts of vinyl acetate in 60 parts of acetone under a pressure of 40 pounds per square inch, the spray being so regulated that the proportion of the fibres in the sliver will be about 85 per cent rayon and 15 per cent vinyl acetate fibres; the sliver thus produced is drafted and spun and then twisted into a yarn in a known manner. After the twisting, the yarn is preheated to a temperature of about 250 F. sumciently long to render the vinyl acetate fibres adhesive and while they are in such an adhesive condition, the yarn is passed through a heated metal eye to compress the fibres while simultaneously the yarn is placed under tension to bring the fibres into more intimate contact with each other, whereupon the tacky vinyl acetate fibres adhere to the other fibres at their points of crossing. Upon cooling to deactivate, the product will be found to have a higher tensile strength, a decreased tendency to untwist, a decreased shrinkage upon washing and less nap than a yarn made in the same manner but composed entirely of rayon staple fibre.

Example II The yarn produced according to Example I is, prior to activation, woven into a textile fabric and the fabric is then passed between pressure rolls heated to 250 F. or heated to this temperature while under tension to activate the vinyl acetate fibres. The fabric shows an improved tensile strength, both wet and dry, a decreased shrinkage and a decreased slippage of the yarns one upon the other. 1

Example III In the manufacture of a fiat textile felt there may be used an apparatus shown in Fig. 2 in which cotton fibres are blown in simultaneously with the spraying through the spray gun in a solution comprising 30 parts cellulose acetate, 3 parts triphenyl phosphate, 30 parts acetone and 3'? parts ethyl acetate. The conditions are so adjusted that the solvent is not completely eliminated by the time the fibres are mixed together and deposited on the belt 24. The proportion by weight of cellulose acetate fibres to cotton fibres should be about to 1.00. The layer of fibres is then carried on the belt through the rollers 25 and 26 which are maintained at a temperature of 285 F. whereupon the cellulose acetate fibres in the felt are rendered adhesive and bind the other fibres. If necessary the felt so produced may be subjected to a drying action in a heated chamber to eliminate the residual solvent. The felt will show substantial resistance to abrasion, a relatively strong binding of the fibres and a sufificient compactness for the product to be useful as a shoe interlining.

Example IV The process of Example III is carried out but substituting, for the solution therein used, a solution of 25 parts of polymerized isobutylene (Vistanex) dissolved in '75 parts by weight of toluene, and the inherently tacky fibres so produced are activated by pressure alone.

Example V The process of Example III is carried out by Example VI The process of Example III is carried out but the conduit 22a through which the natural fibres are introduced, is replaced by a second spray gun through which a solution of 40 parts of cellulose acetate dissolved in 60 parts of acetone is dispersed to produce the non-adhesive fibres,

' and through the spray gun la a solution of 40 parts of polyvinyl acetate in 60 parts of acetone is dispersed to form potentially adhesive fibres, the rate of dispersion of the two solutions being so correlated that the fibrous mixture produced comprises 10% of the polyvinyl acetate fibres and 90% of the non-adhesive cellulose acetate fibres. Upon subjecting the fibre mixture to a temperature of 225 F., only the vinyl acetate fibres are rendered adhesive and the cellulose acetate fibres remain unactivated.

' Example VII The process of Example V1 is repeated but the fibre mixture is treated with carbon tetrachloride which activates. the polyvinyl acetate fibres only and pressure without heat is then applied. Upon evaporation of the carbon tetrachloride the adhesive fibres are deactivated.

It is apparent that the present products have many advantages over prior products. For instance, by forming the potentially adhesive fibres concurrently with the mixing, the steps of prespinning and carding such fibres are eliminated.

with all their attendant difficulties. Since the present products contain fibres of smaller diameter than those obtainable by extrusion through rayon spinnerettes, more points of contact are produced upon the activation than are produced from an equal weight of potentially adhesive fibres formed by such extrusion. Thus, a greater effect is obtainable with an equal weight of fibres or the same eiiect can be obtained with a lesser weight of potentially adhesive fibres. The present invention enables one to employ cheaper fibreforming materials and also materials not physically adapted for forming filaments by rayon spinning methods and permits the incorporation in the fibre-forming composition of a wider variety of additional ingredients, in particular, a wider variety of plasticizers. Furthermore, this invention permits the use of inherently tacky fibres and fibres which become inactivatable with time, and which, by reason of such characteristics, could not be formed, shipped or manipulated in conventional textile or felting operations. Since the potentially adhesive material is in fibrous form, there is no loss of material during the fabrication of the fibrous structures as would be the case if such adhesive material were employed in the form of particles or powder. In the manufacture of textiles, the present invention simplifies the fibre mixing step since no carding of the fibre mixture is necessary. Further, the potentially adhesive fibres do not have to be of the same length or denier as the textile fibres. In the manufacture of felts the present invention permits the direct manufacture of such products 13 with the elimination of fulling, pouncing, wetting, drying and other costly operations. The'present invention enables improved felts to be made from various natural or synthetic fibres and filaments which are smooth-surfaced and/or relatively straight and which consequently do not felt readily.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Certain methods and apparatus described herein are the subject matter of my application, Serial No. 792,020, filed December 16, 1947, as a division of this application.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. As an article of manufacture, a fibrous product comprising a multiplicity of synthetic fibres formed from a synthetic organic potentially adhesive fibre-forming material, the composition of each synthetic fibre being substantially uniform throughout said fibre, admixed with a multiplicity of non-adhesive fibres, said synthetic fibres having cross-sectional areas varying irregularly throughout the length thereof and being of a smaller diameter than fibres obtainable by extrusion of said fibre-forming material through rayon spinnerettes and consequently contacting said non-adhesive fibres at substantially more points of contact than an equal weight of the synthetic fibres formed by such extrusion.

2. As an article of manufacture, a fibrous product comprising a multiplicity of synthetic fibres formed from a synthetic organic potentially adhesive fibre-forming material, the composition of each synthetic fibre being substantially uniform throughout said fibre, admixed with a multiplicity of non-adhesive fibres, said synthetic fibres having cross-sectional areas varying irregularly throughout the length thereof and being of a smaller diameter than fibres obtainable by extrusion of said fibre-forming material through rayon spinnerettes and consequently contacting said non-adhesive fibres at substantially more points of contact than an equal weight of the synthetic fibres formed by such extrusion, fibres in said product being bonded together as the result of the activation of said synthetic fibres.

3. As an article of manufacture, a fibrous product comprising a multiplicity of synthetic fibres formed from a synthetic organic heat-activatable fibre-forming material, the composition of each synthetic fibre being substantially uniform throughout said fibre, admixed and intermingled with a multiplicity of non-adhesive fibres in an unarrayed manner, said synthetic fibres having cross-sectional areas varying irregularly throughout the lengths thereof and being of a smaller diameter than fibres obtainable by extrusion of said fibre-forming material through rayon spinnerettes and consequently contacting said non-adhesive fibres at substantially more points of contact than an equal weight of the synthetic fibres formed by such extrusion.

fibres in said product being bonded together as the result of the heat-activation of said synthetic fibres.

4. As an article of manufacture, a fibrous product comprising a multiplicity of synthetic fibres formed from a synthetic organic heat-activatable fibre-forming material, the composition of each synthetic fibre being substantially uniform throughout said fibre, admixedwith a multiplicity of non-adhesive fibres, the non-adhesive fibres being arranged substantially parallel to each other and the synthetic fibres being unarrayed, said synthetic fibres having cross-sectional areas varying irregularly throughout the lengths thereof and being of a smaller diameter than fibres obtainable by extrusion of said fibre-forming material through rayon spinnerettes and consequently contacting said non-adhesive fibres at substantially more points of contact than an equal weight of the synthetic'fibres formed by such extrusion, fibres in said productbeing bonded together as the result of the heat-activation of said synthetic fibres.

5. As an article of manufacture, a fibrous product comprising a multiplicity of synthetic resin thermoplastic fibres admixed with a multiplicity of non-adhesive fibres, said thermoplastic fibres having cross-sectional areas varying irregularly throughout the length thereof and being of a smaller diameter than fibres obtainable by extrusion of said thermoplastic material through rayon spinnerettes, and consequently contacting said non-adhesive fibres at substantially more points of contact than an equal weight of the thermoplastic fibres formed by such extrusion.

6. As an article of manufacture, a fibrous product comprisin a multiplicity of synthetic resin thermoplastic fibres admixed with a multiplicity of non-adhesive fibres, said thermoplastic fibres having cross-sectional areas varying irregularly throughout the length thereof and being 'of a smaller diameter than fibres obtainable by the result of the heat-activation of said thermoplastic fibres.

CARLETON S. FRANCIS, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,320 Boeddinghaus May 25, 1943 2,011,914 Schwartz Aug. 20, 1935 2252.999 Wallach Aug. 19, 1941 2,253,000 Francis Aug. 19, 1941 2,277,049 Reed Mar. 24, 1942 2,331,321 Heaton Oct. 12, 1943 OTHER REFERENCES The Textile Fibers, J. Merritt Matthews, 4th ed., John Wiley 8: Sons, Inc., New York, 1924, page 430. (Copy in Div. 22.)

Certificate of Correction Patent No. 2,483,405 October 4, 1949 CARLETON S. FRANCIS, JR.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 15, column 2, line 25, and column 3, line 6, for the patent number 2,357,292 read 2,357,392; column 6, line 40, after the word ends insert of;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 27th day of June, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

